#include <bits/stdc++.h>

using namespace std;

ifstream f ("cuplaj.in");
ofstream g ("cuplaj.out");

vector <int> G[10005];

int n, m, k, x, y, nr;

int l[10005];
int r[10005];

bool done, marked[10005];

bool cupleaza (int node)
{
    marked[node] = 1;

    for (auto it : G[node])
    {
        if (!r[it])
        {
            l[node] = it;
            r[it] = node;
            return 1;
        }
    }

    for (auto it : G[node])
    {
        if (!marked[r[it]] && cupleaza(r[it]))
        {
            l[node] = it;
            r[it] = node;
            return 1;
        }
    }

    return 0;
}
int main()
{
    f >> n >> m >> k;

    for (int i = 1; i <= k; i++)
    {
        f >> x >> y;
        G[x].push_back(y);
    }

    done = 1;

    while (done)
    {
        done = 0;
        for (int i = 1; i <= n; i++) marked[i] = 0;
        for (int i = 1; i <= n; i++)
        {
            if (!l[i] && !marked[i])
            {
                done |= cupleaza(i);
            }
        }
    }

    for (int i = 1; i <= n; i++)
        if (l[i] != 0) nr++;

    g << nr << '\n';

    for (int i = 1; i <= n; i++)
    {
        if (l[i] != 0) g << i << " " << l[i] << '\n';
    }
    return 0;
}